The present invention relates generally to endoscopic surgical equipment and more specifically to phacoemulsification sleeves.
Phacoemulsification involves emulsifying the natural lens in situ using an ultrasonically vibrating hollow needle. The emulsified lens is aspirated out of the eye through the hollow needle simultaneously with the infusion of a saline solution. The saline solution is generally infused through the space between the outside of the needle and a thin, flexible sleeve that is held coaxial with the needle. One of the primary benefits of phacoemulsification is that the lens can be removed through a very small incision. With the recent introduction of foldable intraocular lenses, and the ability to insert these replacement lenses through even smaller incisions, the desirable size of the incision through which the phacoemulsification tip and irrigating sleeve must pass is also becoming smaller.
While the desirable phacoemulsification indsion size has become smaller, the overall diameter of the cutting tip/sleeve combination has remained relatively constant. As a result, the tip/sleeve combination must be used in a very tight wound. While the elasticity of the eye tissue allows adequate manipulation of the tip/sleeve within the wound, this tight wound structure compresses the sleeve around the vibrating tip, allowing heat to be generated by the vibrating tip rubbing against the sleeve. If the amount of heat generated is excessive, burning of the eye tissue can result. A further concern is that when the sleeve is compressed around the cutting tip, the irrigation fluid path between the tip and the sleeve is restricted, thereby reducing the flow of the cooling irrigation fluid.
There have been numerous attempts in the past to prevent the sleeve from being collapsed around the cutting tip. For example, U.S. Pat. Nos. 5,084,009, 5,286,256, 5,354,265 (Mackool) and 5,282,786 (Ureche) describe infusion sleeves having a flexible component and a rigid component. The flexible component allows the cutting tip to be manipulated within the eye while the rigid component helps prevent the sleeves from being collapsed around the cutting tip. U.S. Pat. Nos. 4,808,154 (Freeman) and 5,188,589 (Wypych) describe sleeves having grooves or other texturing within the sleeve that allows irrigating solution to flow through the tip even when the sleeve is collapsed around the cutting tip.
While these prior art devices can reduce the amount of friction generated heat, all of these devices allow the cutting tip to contact the sleeve, particularly as the size of wound is decreased. Thus, heat can still be transmitted to the ocular tissue. Accordingly, a need continues to exist for a device that more effectively insulates the cutting tip from ocular tissue.